高電壓設備測試（High Voltage Equipment Testing）（英文版） 課件 Worksheet 4 AC Voltage Withstand and

《HighVoltageEquipmentTesting》ACVoltageWithstandandSeriesResonanceWithstandTest主講人：何發(fā)武（副教授）OperatingWorksheet：WithstandVoltageTestOperatingWorksheet：WithstandVoltageTestTableofContents01Followme02Workshop03Training01FollowmeⅠ.OverviewofACWithstandVoltageTestDuetofactorssuchasmoisture,insulationaging,anddamage,theinsulationperformanceofelectricalequipmentmaydeteriorate.TheACwithstandvoltagetestisthemostdirectandeffectivemethodtoevaluatetheinsulationadequacyofelectricalequipment.Thepurposeofthetestistoassesstheinstallationqualityandinsulationstrengthoftheelectricalequipment.Generally,thewithstandvoltagetestisconductedduringequipmenthandover,majorrepairs,andannuallyafterpassingtheinsulationpreventivetesttopreventinsulationaccidents.Ⅰ.OverviewofACWithstandVoltageTestSincetheACwithstandvoltagetestisadestructivetest,priortestssuchasinsulationresistance,DCleakagecurrent,anddielectriclossmustbeperformedonthetestspecimen.OnlywhenthetestresultsarenormalcantheACwithstandvoltagetestbeconducted.Ifpoorinsulationconditionssuchasmoistureandlocaldefectsarefoundintheequipment,theyshouldbedealedwellbeforeconductingthewithstandvoltagetesttoavoidunnecessaryinsulationbreakdown.Newlyinstalledoil-insulatedequipment,suchastransformersandcircuitbreakers,alsorequireawaitingperiodofatleast48hoursforallgasbubblestoescapefromtheoilbeforethetestcanbeperformed.Ifitisgas-insulatedelectricalequipment,thetestshouldbeconductedunderthelowestallowablegaspressuretoeasilydetectinternalinsulationdefects.Ⅰ.OverviewofACWithstandVoltageTestThewithstandvoltagetestcanbedividedintothefollowingcategories:powerfrequencywithstandvoltagetest,inducedvoltagewithstandvoltagetest,andimpulsevoltagetest.ThepowerfrequencywithstandvoltagetestincludesconventionalpowerfrequencyACtests,powerfrequencyresonancewithstandvoltagetests,and0.1

Hzultra-lowfrequencywithstandvoltagetests.Ⅱ.PowerFrequencyACWithstandVoltageTestThepowerfrequencyACwithstandvoltagetestequipmentisshowninFigure2-16.Figure2-16

PowerfrequencyACwithstandvoltagetestequipmentⅢ.ResonantWithstandVoltageTest1.SeriesResonantWithstandVoltagePrincipleWhenconductingwithstandvoltagetestsonhigh-voltagecapacitivetestobjectssuchasthegenerator,transformer,powercable,GIS(GasInsulatedSwitchgear),switch,bushing,andtransformer,aseriesorparallelresonantdevicecanbeemployed.Inthecaseofseriesresonanttesting,anexcitationtransformerandreactorareutilized.Theseriesresonantpowersourcetakesadvantageoftheresonancebetweenthereactorandthecapacitanceofthetestobjecttogeneratehighvoltageandlargecurrent.Thisresultsinasignificantreductionintherequiredpowercapacityofthepowersourcetoonly1/Qofthetestcapacity.Iteliminatestheneedforbulkyhigh-powervoltageregulatorsandhigh-powerfrequencytesttransformers.Theweightandvolumeoftheseriesresonantequipmentaregenerally1/10to1/30ofconventionaltestsetups.1.SeriesResonantWithstandVoltagePrincipleInaseriesresonantstate,whentheinsulationweakpointsofthetestobjectbreakdown,thecircuitimmediatelybecomesdetuned,andthecircuitcurrentrapidlydecreasesto1/Qofthenormaltestcurrent.Thismethodeffectivelydetectstheinsulationweakpointswhilepreventingexcessivecurrentandburndamageattheshort-circuitfaultpoints.Additionally,itavoidstheoccurrenceofovervoltageduringtherecoveryperiod.1.SeriesResonantWithstandVoltagePrincipleThecapacityoftestequipmentrequiredforconductingACwithstandvoltagetestsonhigh-voltage,high-capacityequipmenthasbeenincreasing.Conventionalpowerfrequencywithstandvoltagemethodsoftenfailtomeettherequirementsofon-sitetesting.Therefore,seriesresonanttestingmethodsarewidelyadoptedforon-sitetesting.Theseriesresonanttestingequipmentischaracterizedbyitssmallsize,lowvoltageofthetestpowersource,lowpowercapacity,andgoodwaveformofthetestvoltage.Asaresult,seriesresonanttestingiswidelyappliedinon-siteACwithstandvoltage,inducedwithstandvoltage,andpartialdischargetestsforhigh-voltage,high-capacitypowerequipmentsuchascable,GasInsulatedSwitchgear(GIS),largegenerator,transformer,andcapacitor.1.SeriesResonantWithstandVoltagePrincipleTheseriesresonantwithstandvoltagetestappliesthebasicprincipleofresonancecircuits.Accordingtodifferentadjustmentmethods,itcanbedividedintoinductanceadjustment,capacitanceadjustment,andfrequencyconversionadjustmenttypes.Throughcomparisonsofthethreetypesofseriesresonantdevicesinpracticalapplications,itwasfoundthatfrequencyconversionseriesresonantdevicesaremoresuitableforon-siteneeds.Duringon-siteACequipmenttests,thefrequencyconversionseriesresonantdevicecanfulfillvariousACwithstandvoltagetests.RefertoFigure2-17fordetails.Thedevicehasthreeoperatingmodes:fullyautomaticmode,manualmode,andautomatictuningmanualboostingmode.1.SeriesResonantWithstandVoltagePrincipleFigure2-17

Frequencyconversionseriesresonantwithstandvoltagetestdevice1.SeriesResonantWithstandVoltagePrincipleTherearecommonlyusedmethodsforadjustingtheseriesresonantwithstandvoltagetestinthefield:inductanceadjustmentandfrequencyconversionadjustment.Regardlessofthemethodused,thegoalistoadjustthehigh-voltagecircuitsothattheimpedanceequalstheadmittance,i.e.,L=1/C.Bydoingso,alowervoltagecanbeappliedtotheintermediatetransformer,whilegeneratingahighvoltageQU(Q=L/R=1/CR,whereistheangularfrequencyandCisthecapacitance)acrossthetestspecimen.1.SeriesResonantWithstandVoltagePrincipleWhetherasufficienthighvoltagecanbegeneratedacrossthetestspecimendependsonthefollowingthreeconditions:(1)Whetherthetotalimpedanceofthehigh-voltagecircuitequalsthetotaladmittance.(2)Whetherthequalityfactorofthehigh-voltagecircuitissufficientlylarge.(3)WhetherthevoltageUappliedbytheintermediatetransformerislargeenough.1.SeriesResonantWithstandVoltagePrincipleThemostimportantcomponentoftheinductanceadjustmentdeviceistheadjustableironcorereactor,whichadjuststheinductanceofthereactorbychangingtheairgapoftheironcore.Theadvantageofthisdeviceisthattheinductanceofthereactorcanbemadeverylarge,allowingforhigh-capacitancewithstandvoltagetestsonlarge-capacityspecimens.Moreover,thesizeoftheinductancecanbelinearlyadjusted,allowingtheseriescircuittoreachtheresonancepointpreciselyaccordingtothecapacitanceofthespecimen.Byinitiallyapplyingalowvoltagetoadjusttheinductanceofthereactorandinduceresonanceintheseriescircuit,thevoltagecanthenbeincreasedwhileadjustingtheinductanceofthereactoruntilresonanceoccursatthetestvoltage.Thisapproachensuressafetyandachievescompleteresonanceinthecircuit.Thedrawbackisthatthemanufacturingofthereactoriscomplexandaddsweighttothedevice.1.SeriesResonantWithstandVoltagePrincipleThefrequencyconversiondevicereliesonahigh-powerfrequencyconvertertoadjustthepowersupplyfrequency,allowingthecircuittoreachtheresonancepoint.Theinductanceofthereactorusedinthisdeviceisfixed,whilethefrequencyofthetestpowersupplyvariesdependingonthecapacitance.Thefrequencyconversionseriesresonanttestdeviceutilizestheprincipleofseriesresonance,excitingtheseriesresonancecircuitusinganexcitationtransformer,andadjustingtheoutputfrequencyofthefrequencyconvertertomatchthecircuitinductanceLandspecimencapacitanceC.1.SeriesResonantWithstandVoltagePrincipleInseriesresonance,theresonantvoltageisexactlyappliedtothespecimen.Theadvantagesincludepreciseresonancepointachievement,simpleconstructionofthereactor,lightweight,andhigh-qualityfactorofthecircuit.Thedrawbackistherequirementforahigh-powerpowersupplyandhighstabilityofthepowersupplyvoltageandfrequency.Thefrequencyrangeofthefrequencyconversiondeviceneedstobelargerthanthatoftheinductanceadjustmentdevice.Withtheadvancementofelectronicequipment,thefrequencyconversionmethodisgenerallypreferrednowadays.1.SeriesResonantWithstandVoltagePrincipleThefrequencyconversionseriesresonancetestutilizesfrequencymodulationandvoltageregulation.Itachievescapacitiveresonancebyutilizingtheinductanceofthereactorandthecapacitanceofthetestspecimen.Theexcitationtransformersuppliestheexcitationpowertotheresonancecircuit.Byadjustingtheinductanceorchangingtheoutputfrequencyofthepowersupply,thereactiveimpedanceandcapacitiveimpedanceinthecircuitcanbemadeequal,resultinginaresonantstateinthecircuit.Inthisstate,thereactivepowerinthecircuittendstozero,andthecircuitcurrentismaximizedandinphasewiththeinputvoltage.ThisenablestheinductanceorcapacitorterminalstoobtainavoltagethatisQtimeshigherthantheexcitationvoltage.ThismethodisparticularlysuitableforACwithstandtestingcircuitsoflarge-capacityandhigh-voltagetestspecimens.Asshownintable2-8.1.SeriesResonantWithstandVoltagePrincipleTable2-8

Selectionofresonanttestvoltageandtestspecimens2.ResonantWithstandVoltageDeviceThecharacteristicofafrequency-variableseriesresonanceACtestdeviceisthatthetuningreactorhasasmallweightandsimplestructure,makingitmoresuitableforon-sitetestingofhigh-capacityequipment.Thewiringprincipleofthefrequency-variableseriesresonanceisshowninFigure2-18.Figure2-18

Frequency-variableseriesresonanceprinciple2.ResonantWithstandVoltageDeviceTheseriesresonanceACwithstandtestdevicemainlyconsistsofavariablefrequencypowersupply(host),anexcitationtransformerT,aresonancereactorL,andcapacitorvoltagedividersC1andC2,asshowninFigure2-19.Figure2-19

Seriesresonantwithstandvoltage2.ResonantWithstandVoltageDevice(1)Variablefrequencypowersupply.Avariablefrequencypowersupplyisapowersourcewithadjustablefrequencywithinacertainrange,asshowninFigure2-20.Theoutputpowerofthevariablefrequencypowersupplyisgenerallygreaterthantheoutputcapacityoftheexcitationtransformer,andthefrequencyadjustmentrangeis20to300Hz.Figure2-20

Variablefrequencypowersupply2.ResonantWithstandVoltageDevice(2)ExcitationtransformerT.TheexcitationtransformerTprovidestheexcitationpowersupplyfortheresonancecircuit.Itexcitestheseriesresonancecircuit.Byadjustingtheoutputfrequencyofthevariablefrequencycontroller,thecircuitinductanceLandthetestobjectcapacitanceCareseriesresonated.Theresonancevoltageisthenappliedtothetestsample.Whenwiring,thehigh-voltagetailXoftheexcitationtransformermustbegrounded.2.ResonantWithstandVoltageDevice(3)ResonantReactorL.Theresonancereactorisusedtoresonatewiththecapacitiveequipmentinthetestcircuitandobtainhighvoltage.Thecapacityoftheresonancereactorcanberelativelylargetomeettherequirementsofthetest.Theratedvoltageoftheresonancereactorshouldmeettherequirementsofthetestvoltage,anditsratedcapacityshouldmeettherequirementsofthetestcapacity.Thereactorcanbeafixedsingle-stagereactororanadjustablereactoradjusteddirectlythroughknobsontheinstrument.Thesingle-stagereactorcanbeflexiblycombinedinseriesorparallel,makingitconvenienttomeettheneedsofon-sitetesting.2.ResonantWithstandVoltageDevice(4)CapacitorVoltageDividersC1andC2.Thevoltagedividersareconnectedinparalleltothetestobject.Theyareusedtomeasuretheresonancevoltageonthetestsampleandprovideovervoltageprotection,asshowninFigure2-21.Whencalculatingtheparametersoftheresonancesystem,thecapacitanceofthecapacitorvoltagedividersshouldbetakenintoconsideration.Figure2-21

CapacitorVoltageDividers2.ResonantWithstandVoltageDevice(5)CapacitorCompensatorC.Thecapacitorcompensatorisusedtocompensatefortheinductanceofthetestcircuit,ensuringthatthetestcircuitmeetstheresonanceconditionsandtestrequirements.Theratedvoltageofthecapacitorcompensatorshouldmeetthetestrequirements.Inthepowerfrequencystate,variableinductorsgenerateresonantcurrentwithinaspecificrangewhencombinedwithvariablereactance,fulfillingthetestrequirements.3.ResonantWithstandVoltageWiringandPrecautionsDuringwiring,theresonancereactor,voltagedividers,excitationtransformers,andothercomponentsofthevariablefrequencyseriesresonancetestequipmentshouldbeplacedascloseaspossibletothetestsampletominimizethelengthoftheconnections.Additionally,ashort-circuitgroundingwireshouldbeusedforgrounding.Duringthetest,irrelevantpersonnelshouldnotapproachthevariablefrequencyseriesresonanceequipmentwithoutpermission.SerialresonanceACtestsshouldnotbeconductedoutdoorsonrainydays.Interferenceinpartialdischargetestsduringseriesresonanceshouldbeavoided.3.ResonantWithstandVoltageWiringandPrecautionsStrengthenthefastjointforhigh-voltageleads.Thelengthofthehigh-voltageleadsisusuallyaround10meters,andtheyareexternallycoveredwithmetalhosestoensureauniformsurfaceelectricfieldfortheleads.Thetwoendsofthemetalhosesshouldbereliablyconnected.Maincharacteristicsofseriesresonancesystems:(1)Wideapplicability,smallsize,lightweight,largetestingcapacity,andhightestvoltage.(2)Highsafetyandreliability,simpleoperation,andgoodtestequivalency.3.ResonantWithstandVoltageWiringandPrecautions(3)Theseriesresonancedevicehasahighimpedanceforhigherharmoniccomponentsinthecircuit,resultinginagoodvoltagewaveformforthetestedspecimen.Intheeventofflashoverbreakdownduringwithstandvoltagetesting,theresonanceconditionsarelost,thehighvoltageimmediatelydisappears,andthearcisextinguished,therebyprotectingthetestedspecimen.Ⅳ.OtherWithstandVoltageTests1.0.1Hzultra-lowFrequencyWithstandVoltageTestThe0.1

Hzultra-lowfrequencywithstandvoltagetest,stillconsideredanACwithstandvoltagetest,caneffectivelydetectdefectsincapacitiveequipmentandinspecttheoperationalandinstallationqualityofequipmentsuchasgenerator,transformer,andrubber-insulatingpowercable.Itassessestheinsulationstrengthofthemaininsulationofgeneratorsandtransformers,cableterminations,andintermediatejoints,andcanconducttestingsensitively,asshowninFigure2-22.1.0.1Hzultra-lowFrequencyWithstandVoltageTestFigure2-22

0.1

Hzultra-lowfrequencywithstandvoltagetest1.0.1Hzultra-lowFrequencyWithstandVoltageTestThe0.1

Hzultra-lowfrequencywithstandvoltagetestismoreeffectiveindetectingdefectsintheinsulationattheendsofgeneratorscomparedtothepowerfrequencywithstandvoltagetest.Thereasonisthatunderpowerfrequencyvoltage,thecapacitancecurrentflowingoutfromthebusbarcausesasignificantvoltagedropwhenpassingthroughthesemiconductorcoronaprotectionlayeroutsidetheinsulation,resultinginareducedvoltageonthebusbarinsulationattheends.Inthecaseofultra-lowfrequency,thiscapacitancecurrentisgreatlyreduced,andthevoltagedroponthesemiconductorcoronaprotectionlayerisalsosignificantlyreduced.Asaresult,thevoltageontheinsulationattheendsishigher,makingiteasiertodetectdefects.1.0.1Hzultra-lowFrequencyWithstandVoltageTestWiringmethod:Thetestshouldbeconductedphasebyphase,applyingvoltagetothephaseundertestandshort-circuitingthenon-testedphasestotheground.Thetestdurationforcommissioning

testis60minutes,andforpreventivetest,itis15minutes.2.InducedovervoltagewithstandtestTheinducedovervoltagewithstandtestisoftenappliedtoelectricalequipmentsuchasthetransformerandtheelectromagneticpotentialtransformer.Themethodusedinvolvesapplyingahighvoltagetotheprimarysidethroughsecondarysidevoltageboosting.Thisapproachcanbeusedtotestthemaininsulationofthedeviceundertestandalsoeffectivelyinspectlongitudinalinsulation,oftenusingmultiplesof100–400

Hz.2.InducedovervoltagewithstandtestTakingtransformerwithstandvoltagetestasanexample,thepowerfrequencywithstandvoltagetestevaluatestheelectricalstrengthofthemaininsulationofthetransformerwindings.Thisincludesinsulationbetweenthehigh,medium,andlowwindingsandthegroundedpartssuchastheironcoreandoiltank.Inducedovervoltagewithstandtestscanfocusonthemaininsulationandthelongitudinalinsulationofthewindings(insulationbetweenturns,layers,andsections),generallyusingdouble-frequency(100

Hz)ortriple-frequency(150

Hz).Theexcitationvoltagefrequencyoftheinducedvoltagetestshouldtypicallybethreetimesthefrequency(150

Hz)andshouldnotexceed400

Hz,withthewithstandtimebeing60×100/f(s)andthedurationnotlessthan20s.3.ImpulseVoltageTestTheimpulsevoltagetestismainlytotesttheabilityofthetestobjecttowithstandtheoperatingwaveovervoltageandtheatmosphericovervoltage.Itisdividedintotheoperatingwaveimpulsevoltagetestandthelightningimpulsevoltagetest.TheimpulsevoltagetestismainlyconductedtoassesstheinsulationwithstandcapabilityoftheDUT(DeviceUnderTest)againstoperatingimpulseovervoltagesandatmosphericovervoltages.Itcanbedividedintooperatingimpulsevoltagetestsandlightningimpulsevoltagetests.Regardlessofthetypeofwithstandvoltagetest,suitabletestequipmentshouldbeselectedbasedonthenameplateparametersoftheDUT,testvoltagemagnitude,andtheexistingtestequipmentconditions,inordertomeettherequirementsofthetest.3.ImpulseVoltageTestDuringon-sitearrangementandwiring,payattentiontomaintainingasufficientsafetydistanceforbothhighvoltagetogroundandtestpersonnel.Thehigh-voltageleadsshouldbesecurelyandasshortaspossible,andthenon-DUTphaseandequipmentshellshouldbereliablygrounded.Aftercompletingthewiring,thepersoninchargeshouldcarefullyinspectthecapacity,range,andpositionofthetestequipment,ensuringthatthevoltageregulatorindicatorisatzeropositionandthatallconnectionsarecorrectanderror-free.02WorkshopⅠ.Testpreparation1.Understandtheon-sitesituationoftheDUTandthetestconditionsConductsitesurveyandreviewrelevanttechnicaldocuments,includingtheannualtestdataandrelatedregulationsoftheequipment,inordertounderstandtheoperationanddefectsoftheequipment.2.TestinstrumentandequipmentpreparationSelectappropriatetesttransformerandcontrolpanel,series-resonanthigh-voltagewithstanddevice,protectiveresistor,spheregap,voltagedivider,digitalmultimeter,megohmmeter,dischargerods,insulationoperatingpole,groundingwire,high-voltagecable,multimeter,Hygrometer,electricalcommontool,safetybelt,helmet,temporarysafetybarrier,sign,etc.Checkthevalidityperiodofthecalibrationcertificatesforthetestinstruments,equipment,andinsulationtools.3.TesttransformerinspectionUsea2.5

kVmegohmmetertochecktheinsulationresistanceofeachwindingtothecasingandground.Checkifthehigh-voltagecoilcircuitisconnectedbymeasuringtheresistancevaluebetweenthehigh-voltageterminalusingamultimeterwitha1

kVrange.Thepointershouldclearlydeflecttowardsthedirectionoflowerresistance.4.Issueworkpermitsandimplementon-sitesafetyandtechnicalmeasuresExplaintheworkcontent,energizedareas,on-sitesafetymeasures,andpotentialhazardstoothertestpersonnel,clearlyassigntasksandspecifythetestprocedures.Ⅱ.PowerfrequencywithstandvoltagetestoperationThepowerfrequencywithstandvoltagetestcircuitconsistsofatesttransformer,voltageregulatorequipment,measurementcircuit,control,andprotectioncircuit,etc.1.TestwiringTheprinciplediagramofACwithstandvoltagetestisshowninFigure2-23.Figure2-23

ACwithstandvoltagetestprinciplediagramT1–voltageregulator;T2–testtransformer;R1–protectiveresistor;R2–spheregapprotectiveresistor;F–sparkgap;Cx–testobject;Cl,C2–capacitivevoltagedividerhighandlowarms;PV-voltmeter.1.TestwiringIntheACwithstandvoltagetest,measuressuchasconnectingtheprotectiveresistorR1,installingdischargesparkgapsF,andsettingovervoltageprotectionaretakentoensurethesafetyofthetestpersonnelandotherrelevantstaffandpreventequipmentandpersonalaccidents.Theprotectiveresistorisconnectedtotheoutputterminalofthetesttransformertolimitshort-circuitcurrentsandsuppressovervoltagescausedbyhigh-frequencyoscillationsduringdischarge.Theactionvoltageoftheovervoltageprotectionissetat1.1to1.5timesthetestvoltage,andtheactioncurrentoftheovercurrentprotectionissetat1.3to1.5timesthecurrentinthespecimen.1.TestwiringOnceovervoltageorovercurrentoccurs,thetestpowersupplyisdisconnected.ThetestspecimenisconnectedtotheprotectivesparkgapGatbothendstopreventtheoccurrenceofresonantovervoltagesinthetestcircuit,andthedischargevoltageissetat1.10to1.50timesUt(thetestvoltage).ACwithstandvoltagetestwiringdiagramisshowninFigure2-24.Figure2-24

ACwithstandvoltagetestwiringdiagram2.TestprocessFirst,adjusttheprotectivesparkgap.Removethehigh-voltageleadconnectedtothetestobjectandshort-circuittheammeterconnectedtothegroundingterminalofthetesttransformer.Adjustthedistanceoftheprotectivesparkgapandthenclosethetestpowerswitch.Slowlyandevenlyincreasethevoltagebyadjustingthevoltageregulator.Thevoltageshouldbeincreasedfromzero,andarapidincreaseinvoltageisallowedbeforereaching40%ofthetestvoltage.Afterthat,thevoltageshouldbeincreasedevenlyatarateof3%persecondofthetestvoltage.Adjustthedischargevoltageto1.1to1.2timesthetestvoltageandthendecreaseittothetestvoltagevalue.Keepthevoltageconstantfor1minuteandobserveifthereareanyabnormalitiesinvariousmeters.Finally,decreasethevoltagetozeroanddisconnectthetestpowerswitch.3.WithstandVoltageTestAftercompletingtheabovesteps,securelyconnectthehigh-voltageleadtothetestspecimenandclosethepowerswitchtoinitiatevoltageincrease.Thevoltagecanbequicklyanduniformlyincreaseduntilitreaches0.75timesthetestvoltage.Subsequently,continuetoincreasethevoltageatarateof2%perseconduntilthedesiredtestvoltageisreached.Thetestvoltageshouldbesustainedforaspecifiedduration,usually1minute.Oncethewithstandvoltagetestiscompleted,promptlyreducethevoltagetozero,openthepowerswitch,groundthetestspecimen,andavoidabruptlycuttingoffthepowerwithoutvoltagereduction.3.WithstandVoltageTestThroughouttheprocessofvoltageincreaseandvoltageendurance,closelymonitorvariousinstrumentreadingsforanyabnormalities,aswellasinspectthetestobjectforsignsofarcing,smoking,burning,charredodors,ordischargesounds.Ifanyofthesephenomenaoccur,immediatelyanduniformlydecreasethevoltagetozero,disconnectthepowerswitch,groundthetestspecimen,andconductanalysisandassessmentforpotentialissues.Afterthewithstandvoltagetest,thoroughlyexaminethetestobjectandperforminsulationresistancetestingtoevaluatetheinsulationconditionpost-test.Fororganicinsulation,afterthewithstandvoltagetest,power-off,grounding,anddischarge,thetestpersonnelcansafelytouchitbyhandtocheckforanysignsofheating.3.WithstandVoltageTestWhenthetestobjectismadeoforganicinsulationmaterial,immediatelytouchitafterthetestdischarge.Ifheatisgenerated,itindicatespoorinsulation.Addresstheissueandconductthetestagain.Forequipmentwithlaminatedinsulationororganicinsulationmaterials,iftheinsulationresistanceafterthewithstandvoltagetestdecreasesby30%comparedtobeforethetest,inspectthetestsampletodetermineitsqualification.3.WithstandVoltageTestDuringthevoltageincreasetest,ifsignificantfluctuationsinthevoltmeterorammeterpointer,anincreaseincurrentwithoutavoltagechange,smoke,burningsmell,flashover,orbreakdownofthetestsampleareobserved,immediatelystopthevoltageincrease.Afterreducingthevoltageandcuttingoffthepower,investigatethecause.Ifitisdeterminedthatthesephenomenaarecausedbyinsulationfailure,theACwithstandvoltagetestisconsideredunsuccessful.3.WithstandVoltageTestDuringthetest,ifsurfacetrackingdischargeorairdischargeoccursduetofactorssuchashighhumidity,temperature,orsurfacecontamination,itshouldnotbeconsideredasafailureoftheinternalinsulationofthetestsample.Aftercleaninganddrying,conductthetestagain.Setupprotectivebarriersandhavesomeonemonitorthem.Ifanyabnormalityisfound,immediatelyturnoffthepower,stopthetest,andfindoutthecause.Ⅲ.OperationofVariableFrequencyResonanceWithstandVoltageTest1.TestWiringThewiringforthevariablefrequencyseriesresonancewithstandvoltagetestisshowninFigure2-25.(a)Wiringforvariablefrequencyseriesresonancewithstandvoltagetestofcross-linkedpolyethylenecables.(b)Schematicdiagramofthewiringforvariable-frequencyseriesresonancetestofathermalpowergeneratorFigure2-25

Thewiringforthevariablefrequencyseriesresonancewithstandvoltagetest2.Testprocedures(1)Arrangethetestequipmentproperly,setupahigh-voltagechargedareaandatestoperationarea,andgroundtheexcitationtransformer,resonantreactor,theenclosureoftheteste